Method and system for automating membership discovery in a distributed computer network

ABSTRACT

A system and methods for automating membership discovery in a distributed computer network is presented. A first virtual circuit label switch path (LSP) associated with a first VPLS is established between a first multi tenant unit (MTU) and an attached provider edge (PE) device. A first label mapping message (LMM) is communicated over the first virtual circuit LSP and received at the PE device. The PE device broadcasts the LMM to a plurality of additional PE devices. In addition, methods for automating membership discovery for adding and deleting virtual private LAN service (VPLS) sites are presented. A virtual circuit forwarding equivalence class (VC-FEC) type packet utilized in the various methods and system is also disclosed.

BACKGROUND

1. Field of the Invention

The present disclosure relates generally to distributed computernetworks, and to the automation of membership discovery in a distributedcomputer network.

2. Description of the Related Art

A virtual provider local area network (LAN) service, also known as aVPLS, is a class of virtual provider networks (VPNs) that allow multiplecustomer sites to be connected where the sites appear to be on the sameLAN (distributed network). VPLS service is typically offered over aprovider managed Internet protocol/multi label switching (IP/MPLS)infrastructure. A VPLS could have up to a few hundred, or even thousandsof sites across the entire distributed network.

Based upon the VPLS architecture model described in Internet EngineeringTask Force (IETF) documents, the following manual provisioning steps mayneed to be repeated when adding, deleting, or modifying a customersite: 1) Add, delete, or modify a customer site to an attached multitenant unit (MTU); 2) Add, delete, or modify a MPLS VC (multi-protocolswitch path virtual circuit) between the MTU and its attached physicaledge (PE) device; and, 3) Add, delete or modify a MPLS VC between a pairof PEs that are associated with the VPLS.

Manually configuring a large quantity of VPLS service sites requiressignificant coordination efforts for site-to-site connectivityprovisioning. Due to the nature of the provisioning complexity, manualsteps often cause mistakes and troubleshooting difficulties, and slowdown the overall service provisioning process.

Accordingly, a need exists for an improved method and system forprovisioning of distributed computer networks.

BRIEF DESCRIPTION OF THE DRAWINGS

The use of the same reference symbols in different drawings indicatessimilar or identical items.

FIG. 1 is a simplified block diagram illustrating a Virtual Private LANService over MPLS (a distributed computer network);

FIG. 2 is a block diagram illustrating a method for VPLS membershipdiscovery between an MTU and its corresponding (provider edge) PE, aswell as between local and remote PEs.

FIG. 3 is a block diagram illustrating another method for VPLSmembership discovery between an MTU and its corresponding (provideredge) PE, as well as between local PE and remote PEs.

FIG. 4 is a flow diagram illustrating a method for automating VPLSmembership discovery and MAC/site-ID learning in a distributed computernetwork;

FIG. 5 is a flow diagram illustrating another method for automating VPLSmembership discovery and site-ID learning;

FIG. 6 is a block diagram illustrating a FEC (forwarding equivalenceclass) field to represent a MPLS virtual circuit for VPLS membershipdiscovery between an MTU and its corresponding (provider edge) PE, aswell as between local PE and remote PEs; and

FIG. 7 is a block diagram illustrating a prior art FEC field torepresent a MPLS virtual circuit utilized for VPLS membership discoverybetween an MTU and its corresponding PE device, as well as between localand remote PEs.

DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

The present disclosure is generally directed to automating discovery ofdevice membership in a virtual private local area network service (VPLS)site over a distributed computer network. In a particular embodiment, amethod is presented for automating membership discovery in a distributednetwork such as a virtual provider local area net service (VPLS). Themethod includes establishing a first virtual circuit label switch path(VC LSP) between a first multi tenant unit (MTU) device and a provideredge (PE) device attached to the MTU, the VC LSP being associated with afirst virtual private local area network service (VPLS) site. A firstlabel mapping message (LMM) communicated by the MTU is received at thePE device, and the PE attached PE device sends a second LMM to the MTUdevice. The second LMM serves to establish a bi-directional virtualcircuit (VC) label switch path (LSP). The attached PE then broadcaststhe first LMM to a plurality of additional PE devices.

In another embodiment, a second virtual private LAN service site isadded to the distributed computer network. The second virtual privateLAN service site is attached to the first multi tenant unit device. Asecond LMM, with a first virtual circuit (VC) label associated with thefirst VC LSP and a non-updated site identification (ID) list, isbroadcast to the plurality of additional PE devices.

In an embodiment, a first virtual circuit label switch path (VC LSP) isestablished between a first multi tenant unit (MTU) device and aprovider edge (PE) device attached to the MTU. The VC LSP is associatedwith a first virtual private local area network service (VPLS) site. Afirst label mapping message (LMM) communicated over the first VCLSP isreceived at the PE device, and the first LMM is broadcast by the PEdevice to a plurality of additional PE devices. In a particularembodiment, the first label mapping message has an identical virtualcircuit label and an updated site identification (site ID) list withrespect to a second label mapping message.

In a further embodiment, a virtual circuit forward equivalence class(VC-FEC) packet to automate membership discovery in connection with aservice provider distributed network is presented. The VC-FEC packetincludes a first field to identify a VC encapsulation type, a secondfield to identify a group identification element, a third field toidentify a VC connection, an interface parameter field to define a MTUdevice parameter, and a sub-tag length value field specifying aparticular site identifier associated with an origination site of thevirtual circuit forwarding equivalence class packet.

In another embodiment, a multi-protocol label switching (MPLS) system isdisclosed. The system comprises a first computing node and a secondcomputing node coupled to the first computing node. The second computingnode receives and stores a VC-FEC packet for use in automatic membershipdiscovery.

In a particular embodiment, a method is presented for automatingmembership discovery in a distributed network such as a virtual providerlocal area net service (VPLS) network. The method includes establishinga first virtual circuit label switch path (VC LSP) between a first multitenant unit (MTU) device and a provider edge (PE) device, e.g., arouter, attached to the MTU, and establishing a VC LSP between a localPE and a remote PE. Multi-protocol switch path virtual circuit (MPLS VC)connectivity among customer sites is automatically established across aprovider's network using Label Mapping Messages (LMMs), as defined inInternet Engineering Task Force (IETF) document Label DistributionProtocol (LDP) Specification RFC 3036, and LDP message relay mechanismsdescribed herein. A PE device performs address learning when a customerpacket is received for the first time on the PE device. In response tothe discovery process and address learning, a site identification (ID)table, e.g., an address table, is created/updated at the PE device.Then, customer packet forwarding follows the proper VC LSP, based upon alookup to the address learning table at the PE device.

In a particular embodiment, another method is presented for automatingmembership discovery in a distributed network such as a virtual providerlocal area net service (VPLS). The method includes establishing avirtual circuit label switch path (VC LSP) between a multi tenant unit(MTU) device and a provider edge (PE) device attached to the MTU, andestablishing a VC LSP between a local PE and a remote PE. The methodalso includes populating an address-learning (site ID-learning) tablealong with membership discovery. MPLS VC connectivity among customersites and address learning is automatically established across theprovider's network using modified Label Mapping Messages with a virtualcircuit forward equivalence class (FEC) and label distribution protocol(LDP) message relay mechanisms described herein. Following the discoveryand address learning processes, customer packet forwarding to the properVC LSP occurs, based on the result of an address (site ID) table lookupat the PE device.

FIG. 1 illustrates, in simplified block diagram form, an embodiment of adistributed computer network. The distributed computer network shown inthe example of FIG. 1 presents three multi-tenant units (MTUs) and theirassociated provider edge (PE) devices; however, it will be appreciatedthat many more MTUs and PE devices could be provisioned and deployed.

The distributed computer network encompasses MTU devices MTU1 110, MTU2120, and MTU3 130, and their respective attached PE devices, which arePE1 102, PE2 103, and PE3 106. In the example of FIG. 1, the MTUs arenot situated in the same geographic location, that is, they areassociated with different sites. Each provider edge device maintains itsown local database, thus PE1 102 has a local database 104, PE2 103 has alocal database 105, and PE3 106 has its local database 109.

In FIG. 1, a multi-protocol label switching (MPLS) network tunnel 101linked switch paths (LSPs) are established between PEs. In addition,targeted label data path (LDP) sessions are set up between PE devices102, 103, and 106. These targeted LDP sessions are indicated by thelines between PE devices 102, 103, and 106, the lines being labeledTargeted LDP Signaling Channel. The targeted LDP sessions are set up inliberal label retention mode. Label Data Path (LDP) signaling channelsessions are set up between MTU1 110 and its attached PE1 102, betweenMTU2 120 and its attached PE2 103, and between MTU3 130 and its attachedPE3 106 device. These channel sessions are indicated by the lines 117between MTUs and their respective PE devices, labeled LDP SignalingChannel in FIG. 1.

In the example of FIG. 1, a label mapping message (LMM) 111 is sent toPE1 device 102, and subsequently broadcast by PE1 device 102 to itspeering PE devices 103 and 106. The information contained in LMM 111 isreceived and stored in each of the databases 104, 105, and 109. The LMM111 is broadcast over a TCP (Transport Control Protocol) session betweenPEs.

FIG. 2 is a block diagram illustrating VPLS membership discovery multitenant units (MTUs) and their respective provider edge (PE) devices. Thesystem illustrated in FIG. 2 contains a number of sites, denoted bycustomer equipment CE1 222, CE2 223, CE3 224, and CE6 225. As before,the particular number of sites, MTUs, and PEs are presented forillustration and are typically of greater number than shown. In theexample of FIG. 2, a virtual label switch path 255 is establishedbetween PE2 203 and MTU5 250 at site CE6 225. Virtual label switch paths235 and 239 are established between MTU1 210 and PE 202, and MTU2 220and PE1 101. In addition, virtual label switch paths 236, 237, and 238are established over MPLS tunnel LSPs between PE devices 202, 203, and206.

In a particular embodiment, a first virtual label switch path such as235 is established between a first multi-tenant unit 210 and itsrespective attached provider edge device 202. The virtual label switchpath 235 is associated with a first virtual private local area networkservice (VPLS) site, such as site 222. A first label mapping message(LMM, not shown) is configured at MTU1 210, and the first LMM iscommunicated over a TCP session to PE device 202. PE device 202 receivesthe LMM, and broadcasts the first LMM to the other PE devices 203 and206 over TCP sessions between PEs.

The information regarding the paths and devices for the established VCsessions is contained in the first LMM, and this information is storedin the respective local databases. An example of this information isshown in the database captions numbered 204, 205, and 209.

If it is desired to add another VLPS site such as site CE3 324 in FIG.3, a second LMM with a virtual circuit label switch path such as 339,associated with the first virtual circuit label switch path 335 isconfigured at MTU2 320. MTU2 320 communicates the second LMM to PEdevice 302. The second LMM contains an updated site identification listfor the addition of CE2 323 VPLS, and the second LMM is broadcast to theplurality of additional PE devices 303 and 306 by PE device 302.

Upon receipt, the information contained in the second LMM is stored ineach PE device's respective database. An example of the informationcontained in the second LMM and stored in the respective PE devices'local databases 304, 305, and 309 is shown in the captions of FIG. 3.

FIG. 4 is a flow diagram illustrating a method for automating VPLSmembership discovery and address learning in a distributed computernetwork. As indicated in the topmost block 400, it is assumed that aliberal label retention mode is used for the label data paths (LDPs)between provider edge (PE) devices. In step 401, an MPLS tunnel andlabel data path (LDP) signaling channel are established. In step 402, afirst VPLS site is added via a MTU device configuration command. The MTUdevice has an attached PE device. In step 403, the MTU device sends afirst LDP label mapping message (LMM) to the attached PE. In step 404,the attached PE receives the first LMM and, in step 405, broadcasts thefirst LMM to a plurality of additional PEs.

In step 406, the attached PE sends a label mapping message to the MTUdevice to establish a bi-directional virtual circuit (VC) label switchpath. In step 407, a second VPLS is added to the same MTU device, thusno membership update is sent to the attached PE. Should another VPLS beadded to a different MTU, an LMM updating membership would be generated,communicated, and stored by the local databases associated with thepeering PEs.

In step 408, a VPLS site is deleted via an MTU configuration command. Instep 410, a decision as to whether this deletion is a final VPLS sitedeletion from the MTU is made. If it is determined that this is thefinal MTU VPLS deletion, then in step 412, the MTU associated with thedeleted VPLS site sends a Label Withdraw Message to its attached PEdevice to release the label. In step 413, the attached PE sends a LabelWithdraw Message to the MTU to release the label in the oppositedirection.

If it is determined in step 410 that the VPLS deletion is not the finaldeletion from an MTU, then in step 411, no Label Withdraw Message issent to the attached PE device. In step 414, a decision is made as towhether a final VPLS site has been deleted from the PE device. If thedetermination is ‘Yes,’ then in step 416, a Label Withdraw Message isbroadcast to a plurality of additional PE devices (peers). If thedetermination in step 414 is no, then no Label Withdraw Message isbroadcast to the plurality of other PE devices, as in step 415.

FIG. 5 is a flow diagram illustrating another method for the automaticdiscovery of VPLS sites and address learning. As indicated in thetopmost block 500, it is assumed that liberal label retention mode isused for the label distribution paths (LDP) between provider edge (PE)devices. In step 501, a MPLS tunnel and LDP signaling channel areestablished. In step 502, a first VPLS site is added via a MTU deviceconfiguration command. The MTU device has an attached PE device. In step503, the MTU device sends a first LDP label mapping message (LMM) with asite identification (site-ID) list to the attached PE. In step 504, theattached PE receives the first LMM and, in step 505, broadcasts thefirst LMM to a plurality of additional remote PE devices. In step 506,the remote PE devices perform site-ID learning by associating thesite-ID with the incoming virtual circuit (VC).

In step 507, the attached PE device sends a LMM to its MTU device toestablish a bi-directional virtual circuit (VC) label switch path. Instep 508, the attached PE device associates the incoming VC with asite-ID in a learning table. In step 509, a second VPLS site is added tothe same MTU device, and the MTU device sends an LMM with the samelabel, but with an updated site-ID list to its attached PE device. Instep 510, the PE updates the learning table by associating the secondsite-ID with the incoming VC.

In step 511, a VPLS site is deleted via an MTU device configurationcommand. A decision is made in step 512 as to whether this VPLS deletionis a final deletion from the MTU. If ‘No,” then in step 513, a LMM withthe same label, but an updated site-ID list is sent to the attached PEdevice. In step 514, the attached PE updates the learning table bydeleting the site-ID entry for the VPLS site being deleted. The attachedPE device then broadcasts the LMM with the updated site-ID list to aplurality of additional provider edge devices in step 515.

If the answer in step 512 is ‘Yes,’ then in step 516, a Label WithdrawMessage is sent to the MTU's attached PE device to release the label,and in step 517, the attached PE device sends a Label Withdraw Messageto the MTU to release the label in the opposite direction.

A final VPLS site to be deleted from the PE device determination is madein decision step 518. If the final deletion answer is ‘Yes,’ then aLabel Withdraw Message is broadcast by the PE device in step 519 to aplurality of additional PE devices (peers). If the answer is ‘No,” thenin step 520, the PE device broadcasts the same LMM with an updatedsite-ID list to a plurality of additional PE devices. In step 521, theremote PE devices update their learning tables by deleting the site-IDentry for the VPLS site being deleted.

FIG. 6 is a general diagram illustrating an example of a virtual circuitfield equivalence class (VC-FEC) packet of the present invention. Thistype of packet may be communicated by the LMM as discussed in thevarious embodiments presented herein. The VC-FEC comprises an unknownbit 610 and a forward bit 611, a FEC TLV type 612, and lengthinformation 614. Field 615 identifies a virtual circuit (VC)encapsulation type, e.g., frame relay, Ethernet, VLAN, ATM VCCtransport, while field 616 identifies a group identification (ID)element. The 32-bit Group ID 616 represents a group of VCs if there isno VC ID present. Another field 617 identifies a virtual circuit (VC)connection identification (ID). An interface parameter field 618 definesa multi tenant unit device parameter. Sub-tag length value fields 619,620 are used to specify a particular site identifier (site-ID)associated with origination of the VC-FEC packet. A site identifiercould identify the provider's media access control (MAC).

FIG. 7 is a general diagram illustrating another example of a VC-FECpacket. Complete specifications for the VC-FEC packet of FIG. 7 arecontained in the Internet Engineering Task Force (IETF) LDPSpecification (RFC 3036). The VC-FEC packet of FIG. 7 is utilized inembodiments of the methods disclosed herein. For example, the variouslabel mapping messages (LMMs) may communicate the packet of FIG. 7, ormay communicate the VC-FEC packet of FIG. 6. Which packet is utilizeddepends upon whether address learning is to be accomplished in the dataplane, e.g. address learning conducted with packet forwarding (packet ofFIG. 7), or whether the auto discovery and address learning processesare performed together (packet of FIG. 6).

The VC-FEC of FIG. 7 comprises an unknown bit 710 and a forward bit 711,a FEC TLV type 712, and length information 714. Field 715 identifies avirtual circuit (VC) encapsulation type, e.g., frame relay, Ethernet,VLAN, ATM VCC transport, while field 716 identifies a groupidentification (ID) element. The 32-bit Group ID 716 represents a groupof VCs if there is no VC ID present. Another field 717 identifies avirtual circuit (VC) connection identification (ID). Field 718 definesinterface parameters for multi tenant unit devices.

The embodiments discussed with reference to FIGS. 6 and 7 of VC-FECpackets are utilized within a multi-protocol label switching (MPLS)system comprising a first computing node and a second computing nodecoupled to the first computing node. The second computing node receivesand stores a VC-FEC packet for use in automatic membership discovery.

The above disclosed subject matter is to be considered illustrative, andnot restrictive and the appended claims are intended to cover all suchmodifications, enhancements, and other embodiments which fall within thetrue spirit and scope of the present invention. Thus, to the maximumextent allowed by law, the scope of the present invention is to bedetermined by the broadest permissible interpretation of the followingclaims and their equivalents, and shall not be restricted or limited bythe foregoing detailed description.

1. A method for automating membership discovery in a distributedcomputer network, the method comprising: establishing a virtual circuitlabel switch path between a first multi tenant unit device and aprovider edge device attached to said multi tenant unit device, whereinthe virtual circuit label switch path is associated with a first virtualprivate local area network (LAN) service site; receiving a first labelmapping message at the provider edge device; sending a second labelmapping message to the multi tenant unit device; and broadcasting thefirst label mapping message to a plurality of additional provider edgedevices.
 2. The method of claim 1, further comprising: adding a secondvirtual private LAN service site to the distributed computer network,wherein the second virtual private LAN service site is attached to thefirst multi tenant unit device; and broadcasting a second label mappingmessage to the plurality of additional provider edge devices, the secondlabel mapping message having a virtual circuit label associated with thefirst virtual circuit label switch path and having a non-updated siteidentification list.
 3. The method of claim 2, further comprising:deleting a third virtual private LAN service site; sending a third labelwithdraw message to release a virtual circuit label, wherein the thirdlabel withdraw message is associated with the third virtual private LANservice site; and broadcasting the third label withdraw message to theplurality of additional provider edge devices.
 4. The method of claim 3,further comprising: sending a fourth label withdraw message to the multitenant unit device to release the virtual circuit label.
 5. A method forautomating membership discovery in a distributed computer network, themethod comprising: establishing a first virtual circuit label switchpath between a first multi tenant unit device and a provider edge deviceattached to said multi tenant unit device, wherein the virtual circuitlabel switch path is associated with a first virtual private local areanetwork (LAN) service site; receiving a first label mapping message atthe provider edge device, the label mapping message communicated overthe first virtual circuit label switch path; sending a second labelmapping message from the provider edge device associated with the firstmulti tenant unit; and broadcasting the first label mapping message to aplurality of additional provider edge devices.
 6. The method of claim 5,wherein the first label mapping message has a common virtual circuitlabel with respect to the second label mapping message and wherein atleast one of the label mapping messages has an updated siteidentification list.
 7. The method of claim 5, further comprising:associating the first virtual circuit label switch path with a siteidentification number in a learning table.
 8. The method of claim 5,further comprising: adding a second virtual private LAN service site tothe distributed computer network; and broadcasting a second labelmapping message to the plurality of additional provider edge devices,the second label mapping message having a virtual circuit labelassociated with the first virtual circuit label switch path and a siteidentification list.
 9. The method of claim 8, wherein the siteidentification list is an updated site identification list.
 10. Themethod of claim 8, wherein the site identification list is a non-updatedsite identification list (when the second virtual private LAN servicesite is attached to the first multi tenant unit device).
 11. The methodof claim 5, further comprising: deleting a third virtual private LANservice site; sending a label mapping message having an updated siteidentification list and a virtual circuit label associated with thethird virtual private LAN service site; updating a learning table inresponse to receiving the updated side identification list; andbroadcasting the label mapping message having the updated siteidentification list to the plurality of additional provider edgedevices.
 12. The method of claim 11, further comprising sending a fourthlabel withdraw message to the multi tenant unit device to release thevirtual circuit label.
 13. A virtual circuit forwarding equivalenceclass packet for use in membership discovery in connection with aservice provider distributed network, the virtual circuit forwardingequivalence class packet comprising: a first field to identify a virtualcircuit encapsulation type; a second field to identify a groupidentification element; a third field to identify a virtual circuitconnection; an interface parameter field to define a multi tenant unitdevice parameter; and a sub-tag length value field specifying aparticular site identifier associated with an origination site of thevirtual circuit forwarding equivalence class packet.
 14. Amulti-protocol label switching (MPLS) system comprising: a firstcomputing node; and a second computing node coupled to the firstcomputing node, wherein the second computing node receives and stores avirtual circuit forwarding equivalence class packet for use in automaticmembership discovery.
 15. The system of claim 14, wherein the virtualcircuit forwarding equivalence class packet comprises: a first field toidentify a virtual circuit encapsulation type; a second field toidentify a group identification element; a third field to identify avirtual circuit connection; an interface parameter field to define amulti tenant unit device parameter; and a sub-tag length value fieldspecifying a particular site identifier associated with an originationsite of the virtual circuit forwarding equivalence class packet.
 16. Amethod for automating membership discovery in a virtual provider localarea network service (VPLS) network, the method comprising: establishinga virtual circuit label switch path (VC LSP) between a multi tenant unitand a provider edge (PE) device attached to the multi-tenant unit;establishing a virtual circuit label switch path between a localprovider edge device and a remote provider edge device; transmitting afirst label mapping message from the multi tenant unit to the attachedprovider edge device; and performing address learning in response toreceiving the first label mapping message.
 17. The method of claim 16,further comprising: receiving, at the attached provider edge device, thefirst label mapping message; and transmitting the first label mappingmessage from the attached provider edge device to the multi tenant unitto establish a bi-directional virtual circuit label switch path.
 18. Themethod of claim 17 further comprising: broadcasting the first labelmapping message from the attached provider edge device to a plurality ofprovider edge devices;
 19. The method of claim 18, wherein the labelmapping message comprises a virtual circuit forwarding equivalence class(FEC) field.
 20. A method for automating membership discovery in adistributed network, the method comprising: establishing a virtualcircuit label switch path between a multi tenant unit and a provideredge device attached to the multi tenant unit; and populating an addresslearning table.
 21. The method of claim 20, further comprising the stepof creating a site identification table.
 22. The method of claim 20,further comprising: receiving, at the attached provider edge device, alabel mapping message; and broadcasting the label mapping message fromthe attached provider edge device to a plurality of provider edgedevices.
 23. The method of claim 22, wherein the label mapping messagecomprises a virtual circuit forwarding equivalence class (FEC) field.24. The method of claim 20, further comprising the step of forwarding apacket based upon the address learning table.